Vehicles powered by external electrical sources, employing a flywheel to store mechanical energy, have been known for years. Usually, the energy storage unit comprises an electric motor arranged together with a flywheel, in a gas tight housing, holding a vacuum or inert gas of the variety lighter than air, ie, helium or hydrogen, under very low pressure. Frequency converters feed energy from the external AC distribution network to accelerate the flywheel through a flywheel motor. During movement of the vehicle, the electric machine operates as a generator, driven by the mechanical energy stored by the flywheel, which energy is converted into electric energy for drive. Such an arrangement is shown in U.S. Pat. No. 3,541,409.
U.S. Pat. No. 3,559,027 discloses an arrangement wherein shock absorber generators convert mechanical energy into electrical energy for battery charging.
U.S. Pat. No. 1,557,570 discloses a concept in which the reciprocating motion of a vehicle utilizes a mechanical coupling between the wheel supports and the frame to power a generator to charge the vehicle battery. However, this patent does not provide means to provide large surges of intermittent charging current to the batteries, nor does it provide a generator similar to the type of the present invention. Also, the patent does not disclose any flywheel or flywheel motor-generator unit.